The formulation of hydrocarbon fuels and lubricants typically includes additives comprising a variety of chemicals to improve properties in application specific situations, particularly gasoline and diesel internal combustion engines. The more commonly used additives include oxidation inhibitors, rust inhibitors, metal passivators, antiwear agents, extreme pressure additives, pour point depressants, detergent-dispersants, lube viscosity index (VI) improvers, foam inhibitors and the like. The scope of the operating conditions to which internal combustion engines are subjected can readily result in lubricant degradation, leading to sludge buildup and excessive engine wear. The foregoing additives serve to control this and other problems in various ways. In the lubricant arts, this aspect is specifically described in Kirk-Othmer "Encyclopedia of Chemical Technology", 3rd edition, Vol. 14, pp 477-526, incorporated herein by reference.
It is known that alkenyl succinimides (ASI) prepared from alkenyl succinic anhydrides (ASA) and polyalkyleneamines are effective as additives to provide ashless dispersancy. These are typically prepared from materials such as polyisobutenyl succinic anhydride and tetraethylene penatamine. Examples of such succinimides are described in U.S. Pat. Nos. 3,024,237, 3,172,892, 3,202,678, 3,219,666 and 3,257,554. The succinimides may comprise mono or bis succinimides prepared according to the following general reaction: ##STR1##
where R is an alkyl or alkenyl of from 8 to 10,000 carbon atoms and R' is the remainder of the polyamine moiety. The term succinimide as used herein includes mono, bis and polysuccinimides as determined by the functionality of the polyamine and molar ratio of reactants.
It is also known that further derivation of alkyl or alkenyl succinimides can be accomplished to enhance the dispersant properties of these succinimides or to augment these properties with additional functions, such as improved antioxidant properties and the like, thereby providing multifunctional additives.
In U.S. Pat. No. 4,482,464 to Karol et al, the reaction product between a polyamine bis-alkenyl succinimide (ASI) and a hydroxy carboxylic acid such as glycolic or 2, 2'- bis hydroxy methyl propionic acid is disclosed. The process comprises coupling with a glycolic acid to form an amido group with the amine of the polyamine. The patent neither discloses nor claims aromatic acids or polyether derivatives thereof.
U.S. Pat. No. 4,713,187 to Buckley et al discloses a bis-ASI polyamine wherein the amine is acylated with oxyl containing a polyether chain and further combined with boric acid or derivative thereof. The patent differs from the present invention in one part in that an oxalic rather than phthalic acid polyether derivative is used.
U.S. Pat. No. 4,783,275 to Wollenberg discloses lubricant additives comprising polyamino ASI modified by treatment with a lactone to yield polyamino ASI wherein one or more of the basic nitrogens of the polyamino moiety is substituted with a hydrocarbylcarbonyl alkylene group. Wollenberg further discloses in U.S. Pat. No. 4,802,893 additives comprising polyamino ASI wherein one or more of the polyamino nitrogens is substituted with hydrocarbyl oxycarbonyl, hydroxy hydrocarbyl oxycarbonyl, or hydroxy poly (oxyalkylene) oxycarbonyl. The invention also discloses and claims the boron product of the adducted ASI. The invention does not teach phthaloyl adducts or phthaloyl adducts containing polyethers.
It is an object of the present invention to provide novel, multifunctional fuel and lubricant additives comprising dicarboxylic acid esters of polyethers and alkenyl or alkyl succinimides.
It is another object of the instant invention to provide a method for producing the foregoing novel, multifunctional additives.
Yet another object of the instant invention is to provide fuel additives having superior dispersant properties.
A further object of the invention is to provide novel fuel and lubricant compositions incorporating the additives of the present invention.